Surface having optically readable printed tags
View Patent ↗A surface having an optically readable pattern of dots printed thereon. The pattern comprises an arbitrarily shaped constant background pattern of dots and/or blanks. The constant background pattern defines discrete areas of coded data represented by a plurality of dots positioned according to an encoding scheme. Each discrete area contains orientation information for enabling an optical reader to determine an orientation relative to the pattern of dots.
1. A surface having optically readable tags printed thereon, each tag comprising:
a background pattern of markings and/or blanks, said background pattern being common to all tags and defining discrete areas;
coded data positioned within said discrete areas, said coded data being represented by a plurality of dots positioned according to an encoding scheme; and
orientation information positioned within said discrete areas, the orientation information being indicative of a rotational orientation of the tag.
2. The surface of claim 1 , wherein each discrete area further contains features usable by an optical reader to determine a perspective distortion of the tag.
3. The surface of claim 1 , wherein the background pattern of markings and/or blanks is distinguishable from the coded data and orientation information.
4. The surface of claim 1 , wherein the coded data in each discrete area is redundantly encoded by the plurality of dots.
5. The surface of claim 4 , wherein the coded data is encoded by Reed-Solomon codewords.
6. The surface of claim 1 , wherein the coded data within each discrete area identifies a page identity which is common to each discrete area on the surface.
7. The surface of claim 6 , wherein the coded data varies between each tag.
8. The surface of claim 1 , wherein said tags are printed with an infrared absorbing ink.